I accept the challenge.
As Con, I will be arguing that the Concealed Carry Laws do not necessarily reduce violent crime (ineffective or may even exacerbate the situation). May both of us enjoy this debate and let's begin.

P.S.
Question: Are we talking about the Concealed Carry laws in general or we must confine ourselves to any specific state?
Request: Please define "violent crime."

We are talking about concealed carry laws in the United States of America

Violent Crime:

"A violent crime or crime of violence is a crime in which the offender uses or threatens to use violent force upon the victim. This entails both crimes in which the violent act is the objective, such as murder, as well as crimes in which violence is the means to an end, (including criminal ends) such as robbery."

MY CASE

1. Concealed Carry Laws Deterre Criminals

Many European nations and the US mainstream media believe that less guns means less crime. This is incorrect.

Before going into crime, we should ask if concealed carry laws deterre crime. The answer is yes. Many economic studies have found that when increased punishments are given to crime, criminals may not committ the crime because the costs outweigh the benefits of committing the crime. Getting shot is a punishment for committing a crime. Many surveys conducted prove that criminals are more scared of people with guns rather than police officers. You can see a police officer, but you don't if a civilian is carrying a gun.

Now let's look at something called "hot burglary". Mr. John Lott calls the act of a criminal robbing a house when a person is already at home "hot burglary". In the United States, 13% of all the burglaries were hot while in Canada and England almost half thew burglaries were hot. The reason is because people would rather go rob places were they know people have no guns (in England and Canada there are strict gun laws) rather than places were someone might own a gun (in the United States people can have guns in their houses). This proves that criminals fear guns.

Concealed carry is also better than open carry. A criminal can see someone openly carry a gun, but he or she cannot see someone carrying a concealed gun. How do you know the person you are going to rob is not armed? This proves that concealed carry is better than open carry. So concealed carry threatens criminals more.

2. The Data Proves that Concealed Carry Reduces Crime

The first data from Mr. Lott, spanning from 1977-1997 shows that murder fell by 7.7%, rape fell by 5.3%, aggravated assault fell by 7.01%, robbery fell by 2.2%, burglary by .5%, larceny by 3.3%, and auto by 7.1%. [2]

The second data from Mr. Lott, which is from 1999, shows that murder fell by 10% and the other crimes fell more greately as well. CCW in his later data slightly changed. [3]

Let's look at some states. In PA murder fell by about 26% and overall violent crime fell by 5.6%. Mr. Lott has proved that CCW laws specifically caused this decrease. The CATO study also finds this. In FL and many other states. [1,2,3]

Both murder with guns and non-guns has dropped considerably from CCW laws (9% and 8.9% respectfully). In addition, CCW laws have prevented mass shooting such as Virginia Tech and then Colorado movie theater. [1]

"If those states which did not have right-to-carry concealed gun provisions had adopted them in 1992, approximately 1,570 murders; 4,177 rapes; and over 60,000 aggravate assaults would have been avoided yearly." [1] [2]

The basis of the argument:

Conclusion

I have proven that concealed carry laws reduce crime rather than increase it through deterrence and data.

Table of Content
1. Introduction
2. Research in Support of Con"s Argument & Evidence Against Pro"s Argument
(a) Paper 1: National Council Council on "More Guns, Less Crime."
(b) Paper 2: More Guns, Less Crime Fails Again: The Latest Evidence for 1977-2006
(c) Paper 3: NBER Working Paper Series
3. Rationale Behind the Numbers
4. Alternative Explanations of "The basis of the argument" Graph
5. Conclusion
6. References

1. Introduction
The debate on the impact of Concealed Carry Laws (hereinafter CCW) on national criminal rate is far from over. About a decade ago, Prof. John Lott, in his book "More Gus, Less Crime", suggested that CCW may be directly responsible for the dramatic fall in crime. Since its issue, the book has drew a range of criticisms. In 2005, the National Research Council (NRC) offered a critical evaluation of the "More Guns, Less Crime" hypothesis and 17 of 18 NRC panels members concluded that the existing research was inadequate to conclude that CCW increased or decreased crime.[1] In their 2009 paper, Prof. Ian Ayres and Prof. John J. Donohue III suggested that CCW may lead to increase in criminal rate six of seven measured categories. [2] Furthermore, in a 2012 paper, Prof. Abhay Aneja, Prof. John J. Donohue III, and Prof. Alexandria Zhang concluded that CCW may increase lead to an increasing rate in aggravated assault.

2. Research in Support of Con"s Argument & Evidence Against Pro"s Argument
(a) National Research Council on "More Guns, Less Crime."
In a 2005 report, National Research Council (NRC) offered an evaluation of the "More Guns, Less Crime" hypothesis. 17 of 18 NRC panel members were not convinced by the research. They concluded that there was no existing credible research that could conclude CCW increased or decreased crime.[1]

(b) More Guns, Less Crime Fails Again: The Latest Evidence for 1977-2006
In their 2009 paper, Prof. Ayres and Prof. Donohue suggests that CCW may actually increase crime in six of seven measured categories (Murder, Rape, Aggravated Assault, Robbery, Auto Theft, Burglary, and Larceny). The research reveals that CCW is associated with increase in Aggravated Assault (+2.64%) while also leads to a decrease in Auto Theft (-1.78%).[2] Prof. Ayres and Prof. Donohue contend that "even if one accepts the facial findings substantially higher aggravated assaults and somewhat lower auto thefts, this would be a bad tradeoff since aggravated assault is much more socially costly than auto theft. In any event, this is not exactly a ringing endorsement of the more guns, less crime hypothesis."[2]

(c) NBER Working Paper Series
In a more recently published paper (August 2012), Prof. Aneja, Prof. Donohue, and Prof. Zhang evaluate the NRC evidence and conclude that the most consistent, albeit not uniform finding to emerge for the research is that aggravated assault rises when CCW is adopted. The researchers, in addition, suggests that for every other crime category, there is little or no indication of any consistent CCW impact on crime.[1]

3. Rationale Behind the Numbers
(a) Even by using the same data set, it appears that researchers may reach vastly different conclusions. The widespread disagreements underscore the complexity of the problem, and perhaps even raise the concerns whether the use of mathematical methods in describing social policy is a sound approach. In determining the relationships between CCW and criminal rate, researchers must decide, according to their own judgments, what kind of control variables should be included; should country level data or state level date be used; what kind of statistical model should be adopted; and how much time after passage of law is enough to determine its effect. [3] The lack of a general consensus may undermine the credibility of research by introducing an increasing number of uncertainties.

(b) In addition to the aforementioned concerns about the role of the statistical analysis in social science study, there are several ways to explain the correlation between CCW and increase in crime.
CCW may provide law-abiding citizens with the opportunity to carry guns in some public places for the purpose of self-protection; it may also keep potential criminals from being caught and detained by the police given the fact that guns can be legally carried in public.
CCW may be proved to be futile or perhaps even encourage the crime in the city where the majority of criminal activity is gang and drug related. It may be one of the reasons behind the increase in murder in Chicago (up 25% from 2011). [4]
A false sense of security could be generated by carrying the concealed weapon. The false sense of security may therefore promote law-abiding citizens to engage in a more offensive and provocative behavior when they face any potential danger, thereby leading to an escalating confrontation with criminals.

4. Alternative Explanations of "The basis of the argument" Graph
Reversed relationship: It is conceivable that the decrease in crime leads to the increase in passage of CCW.
Other factors that may affect the outcome:
(a) Increase in general income level over the past several decades
(b) Increase in the level of education
(c) Increase in the incarceration rate
(d) Increase in the presence of police force
(e) Decrease in the state population
(f) Decrease in the population density
(g) State trends
(h) Unexpected/Sporadic events such as crack cocaine in 1980s and 1990s
(i) Shift in demographic composition: age, race and/or gender

5. Conclusion
Determining the exact relationship between CCW and criminal rates is a demanding task. Given the richness of the data (over 30 years), it would not be surprised that any reference can be drawn from it. A variety of confounding factors such as the incarceration rate and the presence of police force may further complicate the already difficult problem. In no way, however, Prof. Lott"s research is conclusive and Prof. Ayres and Prof. Donohue"s study, by using the same data, reach a complete opposite conclusion. More researches are therefore needed to confirm the causal relationship. Thus, in conclusion, it is premature to conclude that CCW may decrease violent crime.

In his introduction and the argument on research, my opponent cited the National Research Council. It claims that 17 out of 18 of its panel members are not convinced by the research and conclude that there is no existing credible evidence that CCW decreases crime. However, the paper never said Lott was wrong. They said that no firm conclusions can be made. [1]That is not the whole story. NRC findings actually prove Dr. Lott to be correct. Here is part of that:

"A dissenting addendum from James Q. Wilson on this subject concludes that right-to-carry laws "impose no costs but may confer benefits." He points out that the panel's criticisms of the work of AEI scholar John Lott, who first provided data that suggest right-to-carry laws reduce crime and especially murder, are overblown. The panel in fact confirmed Lott's findings in relation to murder, and admitted that the work of Lott's critics had not been subject to the same close analysis as his own." [2]

Lott then made a response to the NRC findings:

"Based on 253 journal articles, 99 books, 43 government publications, a survey that covered 80 different gun-control measures and some of its own empirical work, the panel couldn't identify a single gun-control regulation that reduced violent crime, suicide or accidents."He goes on to say:

"The study was not the work of gun-control opponents: The panel was set up during the Clinton administration, and all but one of its members (whose views on guns were publicly known before their appointments) favored gun control."

And:

"The panel also ignored most of the studies that find a benefit in crime reduction from right-to-carry laws. It did pay attention to some non-peer reviewed papers on the right-to-carry issue, and it also noted one part of a right-to-carry study that indicated little or no benefit from such laws. What the panel didn't point out, however, is that the authors of that particular study had concluded that data in their work did much more to show there were benefits than to debunk it."

So the conclusion is that my opponent's study is flawed for not looking objectively at all the evidence, an overwhelming majority of pro-gun control members, and that the panel actually ignored many studies proving that gun control fails and actually may be counterproductive. [3]Next, my opponent brings up a 2009 paper conducted by Professors Ayres and Donahue. However, their study has not been replicated and it seems that the majority of the studies rule in favor of CCW. [4]Also, I will mention that under 2009 Donahue:"The most conservative estimates show that adopting these so-called "shall issue" or nondiscretionary permit laws reduced murders by 8%, rapes by 5%, aggravated assaults by 7 %, and robbery by 3 %. To put it another way, if those states which did not have concealed handgun laws in 1992 had adopted them, citizens in those states would have avoided suffering approximately 1500 murders, 4200 rapes, over 60,000 aggravated assaults, and 12,000 robberies. Criminals do apparently respond to deterrence." [5]His theory that CCW causes violence is false."Licensees were 5.7 times less likely to be arrested for violent offenses than the general public - 127 per 100,000 population versus 730 per 100,000.Licensees were 14 times less likely to be arrested for nonviolent offenses than the general public - 386 per 100,000 population versus 5,212 per 100,000.Further, the general public is 1.4 times more likely to be arrested for murder than licensees, and no licensee had been arrested for negligent manslaughter." [6]How can CCW cause more crime if the permit holders are extremely law abiding?1) No permit holder has used his weapon improperly on school grounds, ever.2) In Florida, only 0.01% have had their permit revoked--178--almost always for accidentally bringing it into a forbidden area (like a post office). 3) ANY type of firearms revoke (accidental discharge, usually) is rare. "The behavior of permit holders is the easiest question to answer. And Florida is not unusual. The third edition of More Guns, Less Crime presents detailed data for 25 right-to-carry states, and any type of fire- arms-related violation is at hundredths or thousandths of one per- cent."

Arguing it increases aggravation is unlikely, these permit holders are the most law abiding minority in the country. [4]My opponent then discussed Chicago and that its raising crime rates are because of CCW laws. This is untrue."In Chicago, very few new guns have been allowed and that gun ownership is essentially restricted to relatively well to do areas (see below). Yet it is the poorest parts of the city where crime is the worst and where people need guns the most for self protection. One would thus expect a much bigger change in crime rates from the Heller than the McDonald decisions. Still, for Chicago, the change in the law has not had the bad effect that many had predicted."This is true, crime has in fact gone down overall in Chicago rather than up.

My opponent has argued that there is no consensus that CCW laws create positive results. This is untrue. Many studies use Dr. Lott's same data and technique. If he was correct, then the other studies would show similar results. Eighteen studies find that CCW laws lower crime, ten find it having no effect, and only one shows an increase in crime. Other studies using different results (like Helland and Tabarrok 2004) still replicate. Look here:

'1) Florenz Plassmann and Nicolaus Tideman find that "right-to-carry laws do help on average to reduce the number of these crimes."

2) Carl Moody explains that his findings "confirm and reinforce the basic findings of the original Lott and Mustard study."'This is just a few out of many studies findings that replicate.

ADZ

My opponent has cited this ADZ study, but please note it has coding errors:

"1) The observations for county 2060 in Alaska are repeated 73 times for 1996. .2) The first full year of the shall-issue law for Kansas is coded as 1996 when in fact the law was not passed until 2006.3) The first full year of the shall-issue law for Florida is coded as 1989 when in fact the law was passed in 1987.4) The first full year of the shall-issue law for South Dakota is coded as 1987, however the law was passed in 1985." [7]

Note, The NRC and Dr. Lott had similar results. ADZ said no, look at ours. But the only reason their was different was because of the errors, "As can be seen from the last three columns in Table 1, it is the change in the specification, not these errors in the ADZ data set that prevented them from replicating the NRC estimates." When correcting for the errors, their results disappear.

Conlusion

I have proven that my opponent's NRC study actually helps, rather than hinders, Dr. Lott's studies. His ADZ study has coding errors. His 2009 paper study has not been not replicated. Crime is actually overall going down. There is consensus proving this. CCW laws create positive effects. Vote Pro!

Table of Content
Why is Prof. Lott"s research, at best, inclusive; at worst, mistaken.
Research by Prof. Ayres and Donahue
Consensus & Replication of Research
NRC Research
NBER Working Paper Series (ADZ)
Conclusion
References

1. Why is Prof. Lott"s research, at best, inclusive; at worst, incorrect.
(a) Flaw I: Missing of Incarceration Rate
Although in his book, Prof. Lott includes more than thirty-two variables considered to be influential on the national criminal, incarceration rate, mysteriously, escaped Prof.Lott"s attentions. In their 2009 Report, Prof. Ayres and Prof. Donohue explicitly criticized Prof. Lott by stating that: "Yet how much confidence can we really in the Lott and Mustard specification given that, in addition to its other infirmities, it does not even include a variable known to be a powerful factor in reducing crime - the incarceration rate (Marvell and Moddy 1994; Levitt 1996)? If the incarceration rate, conspicuously missing from Prof.Lott"s report, is correlated with the presence of CCW, the resulting estimates on the impact of these laws would be marred by omitted variable bias. [1] Therefore it is conceivable that CCW may perhaps be ineffective (or may even increase the crime) while other more prevailing factors drive down the overall national criminal rates.

(b) Flaw II: Missing of Crack Cocaine movement in late 1980s and early 1990s.
The rise of the crack cocaine phenomenon, a factor unaccounted for in Prof. Lott"s research, according to many well respected researches, had a powerful effect in increasing murders in the United States in the late 1980s and early 1990s. The national criminal rate dropped dramatically following the events. Given the fact that, during the same period, the numbers of permits is on the rise, it is therefore not unreasonable to assume that "what some of the early paper deemed to be a benefit of passing CCW in reducing murder may well be the effect of crack"s harmful impact on murder in states that chose not to adopt CCW, such as New York and California." [1]

2. Research by Prof. Ayres and Donahue
Pro invalidated Prof. Ayres and Donahue"s study on two separate grounds: first he suggested that Prof. Ayres and Donahue"s results have yet been replicated, thereby implying that their research may perhaps be questionable. Second, Pro suggested that permit holders are extremely law abiding thereby insinuating that their research must be based on some implausible assumptions. I will be addressing his assertions in a reversed order.

(a) Implausible Assumptions
(a1) Observations
Permit holders, although appear to be more law abiding than the general population, have done quite a bit of harm. According to Ms.Rand, the spokesman for the Violence Policy Center, "130 (2010 figure) civilians and nine police officers have been killed and 13 mass shootings have been carried out by people with concealed-weapons permits since May 2007." [2] Some more recent incidents include Colorado theater shooting which left at least 12 dead, and 59 injured. Mr.James Hoimes, the alleged suspect, obtained his weapon legally. [3]

(a2) Theoretical Explanation - Two possible explanations
First, it is plausible to assume that the majority of permit holders are law-abiding citizens while only a few permit holders involve in violent crime because of CCW (easy access to weapons). In this scenario, as long as the percentage of increase in total number of permit holders is greater than the percentage of increase in number of criminals with permits, the overall criminal rate among permit holders would be on decline while the CCW may lead to increase in violent crime. Taken mathematically, let"s assume that we have:

Number of Crimes perpetrated by Permit Holders (hereinafter Number of Crimes)
Criminal Rate among Permit Holders (hereinafter Criminal Rate)

Prior to CCW
Number of Permit holders: 100
Number of Crimes: 10
Criminal Rate: 10%

Permits holder may increase 100% while criminal rate may decrease by 2.5% even If number of crimes increase by 50% because of CCW.

Second, CCW may result in more violences among non-permit holders. For instance, a delusional sense of security may lead permit holders to engage in some unnecessary provocative behaviors when confronting criminals; moreover, non-permit holders may obtain weapons via permit holders.

3. Consensus & Replication of Research
In the field of statistical studies, the similar results obtained by other researchers, providing that they use the exact same regressions models, cannot be used to vouch for the accuracy of one"s research. Please consider the following example:

Assume that we attempt to design a regression model to explain a particular phenomenon, and we impudently assume that A1=A2 in our modeling design. The assumption is therefore built into our models. By utilizing the exact same models and dataset, other researchers may reach the similar results even if it is implausible to assume that A1=A2. The similar result thus, can only be used to prove that there is no calculation error; it cannot confirm the accuracy of the model itself, which remains contentious among peers. Source No.7 in Pro"s argument may make the similar mistake. By using a more comprehensive regression model (adding two specifications: incarceration rate and crack cocaine phenomenon), Prof. Ayres and Prof. Donahue"s research an opposite conclusion: CCW may increase crime.

4. NRC Research
If 17 out of 18 panel members (about 95%) conclude that there is no existing credible research that could conclude CCW increased or decreased crime, it would be constituting a implicit rejection of Prof. Lott"s findings. With only one member dissented from the majority opinion, it is highly likely that the dissent opinion is inaccurate or biased. Dr. Wlison erred in excluding incarceration rate and crack cocaine phenomenon as Prof. Lott did, thereby rendering his analysis biased by omitting imperative variables.[1]

NBER Working Paper Series (ADZ)
According to Pro"s source, "it is the change in the specification, not these errors in the ADZ data set that prevented them from the NRC estimates." Therefore, it is not unreasonable to assume that these errors may not lead to a dramatic change in NBER"s conclusion. Given the fact that the errors are non-essential to the conclusion, people should be expected to accept NBER"s conclusion, which asserts that CCW may increase crime.

6. Conclusion
In analyzing the purportedly relationships between CCW and crime, Prof.Lott"s omission of key variables renders his study dubious, if not spurious. By adopting a more comprehensive model, Prof. Ayres and Prof. Donohue are able to reach a conclusion that CCW may lead to an increase in crime. NBER report further strengthens this position while NRC report is somewhat more equivocate on the matter, albeit 17 of 18 panel members implicitly renounced Prof. Lott"s findings. Although there is much to be done to affirm the relation between CCW and crime, there is a sufficient body of evidence to suggest that CCW does not lead to decrease in crime, if not necessarily increase it.

My opponent makes a false claim regarding Lott's book and study. If you actually read the data, he purposely accounts for these variables and says many times his research confirms these police efforts have the largest impact on crime. He understands fully the importance of incarnation rates and arrest data and almost half of the tables in the book involve incarnation rates in some way shape or form. Interestingly, many of Lott's critics in the academic world have taken the data and replicated it conforming the original results [1].

My opponent has also shpt himself in the foot for this debate. He has forgotten the consensus I have demonstrated (notice he drops that point). 18 academically referred studies show CCW's benefit, 1 shows an increase (my opponent is, then, arguing a huge minority position) and 10 show no effect. Many of those studies, the ten, have been rebutted by Lott and the authors have yet to respond (e.g. Black and Nagin 1998, Duncan's work throughout, etc.) Interestingly, the authors often misread their results. Although many of their tables replicate Lott's results, they focus on the one or two that show a statistically insignificant increase and claim there is likely no effect. It is hard (and impossible) to deny Lott has created a consensus and the majority of the data has supported his point.

2. NRC

My opponent has contradicted himself. First, he says the NRC is a good source, but then says Wilson missed many factors. Ironically, Wilson uses the SAME EXACT data as the panel and flatly points out the data. So my opponent, when saying his data is flawed, admits the NRC data is riddled with error.

Second, my opponent has conveniently again dropped the point. The NRC panel, set up by Clinton, is hugely biassed against Lott. First, most of the scholars (except Wilson) are vehemently anti-gun. They also received $900,000 dollars from the pro-gun control organization the Joyce Foundation. Still, they were unable to prove gun control saved lives. Why? Because they cant. As stated, the NRC data replicated Lotts results almost exactly. As stated, they replicated his results on violent crime. My opponent will ask, then, why not conclude with Lott? As stated, the scholars were biassed and they were funded by gun control organizations. A mental phenomena occurs were they need to give back. Concluding with Lott would be against that rule and, therefore, be impossible. Wilson was the only chap honest enough to do so. The rest denied their own findings and merely said more research is needed, in other words we don't know [1][2][3].

And I reiterate. The NRC did not investigate Donahue or Lott's critics, even though their findings have been widely criticized outside of the panel. Even with the data supporting Lott, being funded by liberal anti-gun foundations, having biased authors, and using one side reporting (not investigating the critics), they DO NOT say Lott is wrong. The majority opinionï¿½€"which my opponent keeps falsely citingï¿½€"merely says we don't know. It is interesting how politics kept them from being honest but they still couldn't deny Lott's findings. If scholars Like Marvel and Moody have overcome skepticism, I do not see why the NRC misrepresented their results. My opponent is wrong on the NRC fiasco.

To conclude on the NRC data, the newest paper on the issue:

"ADZ couldnï¿½€™t replicate the NRC results with the NRC data. They jumped to the conclusion that it was due to bad data from Lott. We now know that the data that Lott provided to the NRC was the same as that provided to hundreds of other researchers. Using Lottï¿½€™s data, we could we replicate the NRC results for both the dummy variable and trend model, corresponding to the NRC Tables 6-1 and 6-2 and, since the NRC was also able to replicate the original Lott and Mustard results, the NRC must have been using the same data. We were also able to replicate the NRC ï¿½€œno covariateï¿½€ï¿½ model for the 1977-2000 sample. We find it hard to believe that ADZ couldnï¿½€™t replicate those results with the NRC data. Researchers cannot be held responsible for errors committed by others who request their data. ... We now know that the data provided to the NRC was not tainted with errors. Therefore James Q. Wilson was perfectly justified to conclude that right-to-carry laws reduced murders, since the NRCï¿½€™s own regressions, based on good data provided by Lott, showed a significant negative effect on crime. Also, all the peer-reviewed studies that are based on Lottï¿½€™s data that find that shall-issue laws reduce violent crime, or at least do not increase violent crime, are not tainted by errors. The record still stands at 18-1-10."[3] the 18-1-10 is the consensus I was talking about.

3. VPC "study" on conceal carry holders

The study my opponent cited, to be frank, is a lie and a biassed report from a gun control organization. It is not peer reviewed, in a scholarly way at least, it uses biassed data and the organization had conclusions made before they even wrote a word. Other then that glaring flaw, lets look at a few more.

Flaw 1: How they identified permit holders

They gathered their data not from the Attorney General or the FBI, but news reports. The media is wrong always on these issues. They cant tell and AR-15 apart from a AK-47, a revolver from a block, I really can't see how this method is valuable or accurate.

Flaw 2: Charged with crime =/= conviction

They went based off of charges, not convictions. The majority of the cases the permit holder was found innocent or the evidence on their side and the accusation unlikely.

Flaw 3: They fail to see data

There has been a drop in police deaths since the 70s and 80s, when these laws began to be passed. Interesting correlation, huh? Interestingly, a study done by David Mustard finds conceal carry laws help police officers and reduce police deaths--seems as though the VPC has academic opponents that do not forge data [4].

Even using their own data, the VPC still shows permit holders commit felonies at a 1/10th as their non permit brothers [5]. The "study" my opponent used has been refuted. The study I citedï¿½€"done by actual scholarsï¿½€"shows permit holders are the most law abiding people in the USA.

4. ADZ

Saying those errors do not affect anything is naive. One county was entered in Alaska 73 times. It likely had an increase, and they did this to bolster findings which shouldn't exist. They put in Kansas 10 years before the law was passed, ruining that state. They enter in Florida two years after the lawï¿½€"hiding its initial decrease in crime that Lott demonstratesï¿½€"to hide data. And did the same to South Dakota. Other studies that enter this in correctly replicate Lott's results [3], studies that have these errors do not. Obviously Lott's data is more accurate as it does not have these timing errors. These coding errors destroy the ADZ analysis.

5. Other factors and recent shootings

Actually, all but one of the mass shooting happen on gun free zones, the recent ones were gun free zones. They never happen in NRA meetings or in areas that allow guns. This refutes my opponents analysis. Also, a 2003 study by Lott and Whitley show CCW decreases mass pubic shootings [5].

Lott and the other studies either controlled for cocaine prices or usage and all got the same results.

My opponent keeps saying Donahue got the opposite conclusion. Yes, he did, using flawed data either with his hybrid model [1], or coding errors. Lott and the 18 studies prevail.

Conclusion:

The NRC study was flawed, and Wilson's dissent is justified. Donahues and the VPC analysis have so many errors it isn't even funny. The 18 studies show CCW is a benefit. Vote pro--out of room.

Summary
In this debate, Pro and I attempt to argue if CCW has any discernible impact on crime. I maintain that CCW does not have any significance impact on crime, if not increases it. As Con, I introduce three independent researches i.e., NRC Report, Prof. Ayres" study ADZ Report, to advance my arguments. My main argument is built around Prof. Ayres" study. The early version (2011) of ADZ report contains some errors which are subsequently corrected in the latest issue (2012). All three reports have concluded that Prof. Lott"s main conclusion is incorrect. By embracing a more comprehensive models in their research, Prof. Ayres is able to conclude that CCW may increase crime. ADZ report further confirms Prof. Ayres"s findings. While Prof. Lott believes that arrest rate alone is enough to measure the significance of deterrence, both Prof. Ayres" report and ADZ report show that it is inappropriate to exclude incarceration rate from the model.

Rebuttal
More Guns, Less Crime Fails Again
Unlike what my opponent claimed, Prof.Lott did not properly account for incarceration rate. To be fair, Prof.Lott did include arrest rate in his study. Prof.Lott, however, omitted incarceration rate in favor of arrest rate alone to measure the impact of deterrence on crime. This particular approach that Prof. Lott and Mustard adopted is especially problematic and it cannot therefore properly account for the significance of incarceration rate. Ideally, one might like a measure showing the likelihood (probability) that one who commits a certain crime will be arrested. [2] Instead, Prof.Lott defines arrest rate as a ratio of arrests to crime, which means that when one person kills many, the arrest rate falls (one arrest/multiple crimes); but when many people kill one person e.g., Drug-related crime, the arrest rate rises. The bottom line, according to ADZ study, the arrest rate under Prof.Lott"s construction is not a probability and is therefore misplaced. [2] By including this eerily defined arrest rate in his model, Prof.Lott has inexorably introduced some intractable uncertainty, thereby compromising the integrity of his findings. On the other hand, Prof. Ayres" study properly accounts for the effect of incarceration rate and crack cocaine phenomenal and reaches a more reasonable conclusion.

Pro also suggested that I willingly dropped some points in our pervious exchange. What my opponent fails to understand is that it is not the number of studies, but the quality of studies that matters the most. Being able to replicate the results would not necessarily imply that the study is scientifically accurate (Round 3). What one can properly inferrer from a successful replication is that scientists do not intentionally manipulate the data. Whether model is sound or reasonable, however, is an entirely different of matter. In fact, it is hard to fathom that a study, which fails to include the single most important variable (incarceration) in its equation would constitute a valid study, let alone the other 18 studies which rely on the same flawed approaches.

NRC Report
The panel (17 out of 18) rejected Prof. Lott"s findings on the ground that his model was too sensitive to some variables to be a valid model. Small changes would make the estimate bounce around so much that is was difficult, if not impossible, to reach any conclusion about the significance of CCW. [2] In other words, NRC panel questioned the soundness of Prof. Lott"s model, not his calculation. On the basis of their own calculation, the panel concluded that the data provided no reliable and robust support for Lott-Mustard contention, even if the panel was able to replicate Prof. Lott"s results.[2] Prof. Wilson, a political scientist (not a statistician) conveniently overlooked the panel"s suggestions in his dissenting opinion. In fact, the results that Professor Wilson found to be consistent evidence of CCW laws reducing murder disappear with better data (from 1977-2000) and a superior specification (by including incarceration rate).[2]

Pro accused me of dropping the point again. In R3, I attempted to explain that the panel rejected Prof.Lott"s findings on the basis of merits alone. I can resort to personal attack as well by claiming that Prof. Wilson"s personal preference and prejudice on the issue may have clouded his judgement while Prof. Lott, on the other hand, is a member of America Enterprise Institute, a conservative think tank that allies with National Rifle Association (NRA), a powerful pro-gun organization that claims to defeat any candidates who may even remotely suggest any gun regulation.[1] I would guess that Prof. Wilson and Prof. Lott have more to lose if they dare to defy the will of NRA. But is there any evidence that may suggest that any of these researchers fabricated their data in an attempt to please their sponsors? The answer is no. Therefore, even if the panel was founded by President Bill Clinton, there is no plausible reason to doubt the integrity of the panel. Pro"s personal attack is therefore self-defeating.

VPC Study
Baseless attack on the source should be rejected. Specifically:
How they identified permit holders
Whether the media is able to tell AR-15 apart from a AK-47 is irrelevant to whether they can identify a person is a permit holder. Just like a person does not need a Ph.D. degree to understand some basic facts about mathematics, there is no compelling reason to suggest that media cannot accurately identify the permit holders.

Charge with crime =/= conviction
I would agree that charge with crime is not same as conviction. But the number I cited is the number of convicted murders, not charges in general. Besides, the majority of the case that the permit holders are found innocent is not serious cases such as rape or murders.

The fail to see data
I merely cited the figures collected by VPC, not its research. Besides, VPC may properly show that permit holders commit felonies at a much lower rate than non-permit holders, but the research does not preclude the possibility that permit holders may commit more violent crimes after the passage of CCW, even if they are, in general, more law-abiding than non-permit holders.

ADZ Report
In their latest report (August 2012), authors specifically acknowledge their coding errors, but maintain their conclusions: "We know all too well how easy it is to make these small but annoying errors in creating these data sets, since regrettably we had a few similar errors in our own data set in the Aneja, Donohue, Zhang (2011) published version, which are all corrected here. None of the main conclusions of the published paper were altered by those errors." [2] Besides it remains a possibility that these aforementioned errors do not have any obvious effect on the main conclusions. For example, although the county 2060 for Alaska are duplicated 73 times for 1996, the county is insignificant in model building. It is a marginal error may not have any material influence on the overall conclusion. As for Florida"e year of adoption, authors (of ADZ) claimed that their country data does not provide crime category information for Florida countries for 1998, so authors elected to drop the observations for the year for all Florida countries. [2] To compensate for the loss of data, authors adjust their model according by beginning the post-passage variable counter with a value of "2" in year 1989. [2] Therefore, although there are some annoying errors in ADZ report, there is no compelling reason to reject their conclusions.

Conclusion
In conclusion, Prof.Lott"s findings should be rejected and more researches are needed to establish a precise relation between CCW and crime.

@khaoToum
The massive shooting should give everyone a pause. But another question raises: would gun control be sufficient or even useful? No one knows. The argument can go both ways:
No guns -> no massive shorting.
Have guns -> stop the gun man -> no massive shooting.
So which argument would prevail? No one knows. I guess the best way to solve this national plight is to keep guns out of the wrong hands. But another question is: how to define this "wrong hands" anyway?

Not everyone with a gun have the heart to take another persons life, and if everyone with a gun have the heart to take another persons life there would be chaos.

10 out of 100 people who has a gun will end up using it, as oppose to 90 out of 100 people who don't have a gun who has never used a gun before and may never get the chance to make a mistake they might regret for the rest of their life.

If people were perfect enough to never forget (leaving their gun laying around where kids can get a hold of it), never get into accidents (as in accidentally shoot an innocent person), never get angry, everyone on earth would never lose their mind (Go crazy and go on a shooting rampage), if their were no envy, jealously, hate nor greed in the world, then I would agree with open concealed in public.

If everyone can carry a gun, then who needs law enforcement?

how ever I do believe that it is OK for people to walk around with their gun in their waste in low crime states, to keep the crime low. but then again if the crime is already low who needs guns besides hunters?

but for high crime states to allow people to walk around with a gun in their waste would just make it worse, because that only makes criminals with no criminal records want to test you to see if you would use that gun even more.

10 out of 100 people who has a gun will end up using it, as oppose to 90 out of 100 people who don't have a gun who has never used a gun before and may never get the chance to make a mistake they might regret for the rest of their life.

If people were perfect enough to never forget (leaving their gun laying around where kids can get a hold of it), never get into accidents (as in accidentally shoot an innocent person), never get angry, everyone on earth would never lose their mind (Go crazy and go on a shooting rampage), if their were no envy, jealously, hate nor greed in the world, then I would agree with open concealed in public.

@PatriotPenguin
But it may increase the overall criminal rate. CCW may work particularly well in some states (Florida perhaps), but it can also be proven to be troublesome (Michigan for example). Public policy is no mathematics, and there is no reliable way can precisely measure the effect of any particular public policy. It should also be noted that if all permit holders were law abiding citizens, people should have nothing to worry about. In that case, there is no need of guns anyway (other than hunting of course).

@16kadams
As for the police rebuttal, are you referring to "Flaw 3: They fail to see data"?
If so, then I must apologize. The reason I dropped the argument is because I was running out of space (I do have rebuttal prepared, but I dropped in editing). It would have taken me at least 200-300 words to go though Pro's report in an attempt to explain the rationale behind my rebuttal. My argument goes like this: the causality is very difficult to establish in this case. Does drop in police deaths lead to the adoption of the law or CCW somehow manages to reduce the causality? Correlation is not the same as causality. Furthermore, some other factors such as tougher laws, better education, and special events would affect the outcome with various degree. I am able to rebut Mr.1Historygenius on a theoretical ground, so does Mr.1Historygenius. That is the reason why I decided to drop the argument.

As for the media report. It is a tough call. Pro did show the flaw in VRC Report in general, but he did not show the flaw in specific. Perhaps I should make it more clear in my argument. "Charged with crime =/= conviction." But this is a general theory. If we had one or two more rounds, I would urge my opponent to show how VRC gets wrong on murder accounts in specific. What is the actual rate? What is the likelihood that charges lead to convictions, in general and in specific. Miscounting the number of convictions by including arrests may bias VRC report in general, but I have yet found reasons to believe that they somehow manipulate the data on the number of murders, specifically. So my principle is: "General is not the same as specific."

@16kadams
Forgot to add year 2010.
Both books (1997 & 2010) are based on his 1997 research paper. Throughout the years, Prof.Lott gradually adds new data and gets his model polished (or adjusted). The first edition collects data from 1977 to 1992, and the latest version includes a new set of data from 1992 to 2006. But for thing, he consistently misstates the incarceration rate. That is the main problem with all the other scholars. That is the central argument in Prof.Ayres and Donohue's paper. In essence, they question the rationale behind Prof.Lott's model, and here comes the problem. If you ever get a chance to check out NBER report (2012 August), starting from page 26, they begins to dive into statistical world. It is way too technical for a layman to understand. But without understanding the statical model, no one would have a complete picture about the disagreement between Prof.Lott and Prof.Ayres's work. So in conclusion, both 1997 and 2010 versions contain similar flaws.

The FBI doesn't rely on news sources. Pro demolished on that point. You dropped his police rebuttal (interesting study he cited) and how EVERY other academic has failed to replicate the VPC's biassed numbers. He showed their failed data collection and, when you research how they got the data, they added arrests and convictions together.

@16kadams
Prof. Lott might talk about the rate all the time, but he did not measure the rate properly. Arrest rate is not the same as incarceration rate.

As for ADZ study, it is just my habit. Due to a variety of reasons, I gradually develop a tendency to read the original report myself instead of relying on media report. It serves me well sometimes, but it also poses some significant problems, like this time.

As for the ad hominem attack. I was referring to Pro's assessment of NRC panels. VPC's number may be contentious, but there is no reason to believe that they fabricate the number of murders. Ideally, it would be nice if Pro can show that VPC mistakenly records the number of murders specifically. Undeniably, it would be more reliable if VPC obtains its information from FBI or other sources, but the same argument can be put forward to dispute the readability of FBI's records as well.

Reasons for voting decision: This was a very informative debate and an easy enough read between pro and con. I was slightly disappointed that more information was not introduced to support either side. Ultimately, it seems the actual impact on crime 'rates' seems to be negligible. My vote goes to Pro because I as a responsible gun owner who knows many others have seen CC weapons used to deter more crimes than those used in the committing of crimes. Congrats on a good effort to both.